resonance_tester: Added a new sweeping_vibrations resonance test method (#6723)

This adds a new resonance test method that can help if a user has some mechanical problems with the printer.

Signed-off-by: Dmitry Butyugin <dmbutyugin@google.com>

docs/Config_Changes.md

@@ -8,6 +8,14 @@ All dates in this document are approximate.
 
 ## Changes
 
+20241203: The resonance test has been changed to include slow sweeping
+moves. This change requires that testing point(s) have some clearance
+in X/Y plane (+/- 30 mm from the test point should suffice when using
+the default settings). The new test should generally produce more
+accurate and reliable test results. However, if required, the previous
+test behavior can be restored by adding options `sweeping_period: 0` and
+`accel_per_hz: 75` to the `[resonance_tester]` config section.
+
 20241201: In some cases Klipper may have ignored leading characters or
 spaces in a traditional G-Code command. For example, "99M123" may have
 been interpreted as "M123" and "M 321" may have been interpreted as

docs/Config_Reference.md

@@ -1790,11 +1790,14 @@ section of the measuring resonances guide for more information on
 #   auto-calibration (with 'SHAPER_CALIBRATE' command). By default no
 #   maximum smoothing is specified. Refer to Measuring_Resonances guide
 #   for more details on using this feature.
+#move_speed: 50
+#   The speed (in mm/s) to move the toolhead to and between test points
+#   during the calibration. The default is 50.
 #min_freq: 5
 #   Minimum frequency to test for resonances. The default is 5 Hz.
 #max_freq: 133.33
 #   Maximum frequency to test for resonances. The default is 133.33 Hz.
-#accel_per_hz: 75
+#accel_per_hz: 60
 #   This parameter is used to determine which acceleration to use to
 #   test a specific frequency: accel = accel_per_hz * freq. Higher the
 #   value, the higher is the energy of the oscillations. Can be set to
@@ -1808,6 +1811,13 @@ section of the measuring resonances guide for more information on
 #   hz_per_sec. Small values make the test slow, and the large values
 #   will decrease the precision of the test. The default value is 1.0
 #   (Hz/sec == sec^-2).
+#sweeping_accel: 400
+#   An acceleration of slow sweeping moves. The default is 400 mm/sec^2.
+#sweeping_period: 1.2
+#   A period of slow sweeping moves. Setting this parameter to 0
+#   disables slow sweeping moves. Avoid setting it to a too small
+#   non-zero value in order to not poison the measurements.
+#   The default is 1.2 sec which is a good all-round choice.
 ```
 
 ## Config file helpers

docs/Measuring_Resonances.md

@@ -694,6 +694,24 @@ If you are doing a shaper re-calibration and the reported smoothing for the
 suggested shaper configuration is almost the same as what you got during the
 previous calibration, this step can be skipped.
 
+### Unreliable measurements of resonance frequencies
+
+Sometimes the resonance measurements can produce bogus results, leading to
+the incorrect suggestions for the input shapers. This can be caused by a
+variety of reasons, including running fans on the toolhead, incorrect
+position or non-rigid mounting of the accelerometer, or mechanical problems
+such as loose belts or binding or bumpy axis. Keep in mind that all fans
+should be disabled for resonance testing, especially the noisy ones, and
+that the accelerometer should be rigidly mounted on the corresponding
+moving part (e.g. on the bed itself for the bed slinger, or on the extruder
+of the printer itself and not the carriage, and some people get better
+results by mounting the accelerometer on the nozzle itself). As for
+mechanical problems, the user should inspect if there is any fault that
+can be fixed with a moving axis (e.g. linear guide rails cleaned up and
+lubricated and V-slot wheels tension adjusted correctly). If none of that
+helps, a user may try the other shapers from the produced list besides the
+one recommended by default.
+
 ### Testing custom axes
 
 `TEST_RESONANCES` command supports custom axes. While this is not really